It is known that the clothing made from cellulosic fabrics such as cotton, in particular, indigo dyed denim can be treated by fabric finishing processes such as prewashing or stonewashing to release dye from the fabric. Such treatment can accomplish a preworn and softer effects that have been preferred by consumers for many years. Indigo blue is the most common dye that is released in the fabric finishing process. Other dyes such as sulfur black are also used to color denim and could also be released in a stonewashing or prewashing process.
In a stonewashing process, fabric, usually denim, is treated to intentionally release dye from the fabric to nonuniformly fade the fabric. This process may also soften the fabric and make the fabric surface appear fuzzy and worn.
In a prewashing process, excess dye is removed from the fabric uniformly to fade the fabric. This process may also be used to soften the fabric by removing the sizing agent present in the fabric, to remove stiffening agent or to preshrink the fabric. Compared to the prewashing process, stonewashing process produces a more preworn look.
A common problem in both stonewashing and prewashing processes is that the released dyes can redeposit back on the same or different fabric. For example, when stone washing blue jeans, the released dye tends to redeposit onto the denim and white pocket liners. Because of the deposition, the pocket liners become undesirably colored and the denim has a darker appearance on the seams of the clothing. The problem of dye redeposition in stonewashing and prewashing is more severe because the concentration of dye in the wash bath of both processes is at least 100 percent higher than in a typical household laundry process.
Consequently, efforts have been made to seek a fabric washing process and a dye deposition inhibiting agent that can be effective in preventing dye from redepositing on fabrics during the washing process.
U.S. Pat. No. 4,444,561 to Denzinger et al. issued Apr. 24, 1984, discloses a process for washing and after-treating textile goods containing synthetic fibers, which utilizes a copolymer as an antiredeposition agent to inhibit the resoiling of the wash with the dirt particles and fats, particularly in the case of fabrics containing synthetic fibers. The copolymer being employed comprises: (a) from 50 to 90% by weight of one or more vinyl esters of C.sub.1, to C.sub.4 aliphatic carboxylic acids, (b) from 5 to 35% by weight of one or more N-vinyl lactams, (c) from 1 to 20% by weight of one or more monomers containing basic groups, or of salts or quaternization products of these monomers, and (d) from 0 to 20% by weight of one or more further monomers which are copolymerizable with monomers (a), (b) and (c) and are free from carboxyl and basic groups.
U.S. Pat. No. 4,925,588 to Berrod et al. issued on May 15, 1990, discloses an antisoiling and anti-redeposition agent which is useful for the aqueous washing of textile articles to avoid the redeposition of the soiling removed during washing on the textile fibers. The antisoiling and anti-redeposition agent comprises a vinyl copolymer of at least one (meth)acrylic ester and at least one unsaturated carboxylic acid grafted with at least 1% polyester sulfonate.
U.S. Pat. No. 5,730,760 to Kirk et al. issued on Mar. 24, 1998, provides a fabric washing composition and aqueous treatment solution for inhibiting deposition of dye, comprising at least one dye deposition inhibiting polymer. The dye deposition inhibiting polymer comprises, as polymerized units, from 5 to 100 weight percent of at least one vinyl amide monomer and from 0 to 95 weight percent of one or more vinyl ester monomers.
It is an object of the present invention to provide a fabric or garment washing composition containing one or more dye deposition inhibiting agents which can be added during fabric finishing processes to effectively inhibit the deposition of dye during these processes.
A further aspect of this invention is to provide a process for washing dyed fabric or garments consisting of natural fibers to inhibit the deposition of released dyes onto the fabric during prewashing or stonewashing.
We have surprisingly found that these objects are achieved by the use of at least one water-soluble or water-dispersible polyester resin disclosed in U.S. Pat. No. 4,977,191 in a wash liquor as a dye deposition inhibiting agent.